The present invention relates to a container valve with a tripping device for stationary fire extinguishing plants.
Great demands are made on a container valve with a tripping device for stationary fire extinguishing plants. It has to: (1) securely block the gas pressure in the extinguishing substance container until the plant is released (in high-pressure plants, the gas pressure in the container can be more than 300 bar); (2) be reliably releasable by a tripping mechanism as simple as possible; (3) offer the emanating extinguishing substance only a low resistance to flow (i.e. comprise a valve seat with a large cross-section); and (4) remain securely opened after the release.
Most of the container valves with a tripping device for stationary fire extinguishing plants are today embodied as so-called articulated-lever valves. However, these valves have the disadvantage that they require a relatively high tripping force for actuating the articulated lever. It has therefore been already proposed to construct container valves with a tripping device for stationary fire extinguishing plants as differential pressure valves. Such a differential pressure valve comprises a closing piston which is mounted in a valve body to be slidably movable in the axial direction and comprises a sealing face at a first end with which it can be pressed against a valve seat. The opposite end of the closing piston is introduced in a tripping chamber to seal it and here embodies a pressure face which is larger than the free cross-section of the valve seat. A pressure compensation channel transverses the closing piston and connects the tripping chamber with an inlet channel. When the valve is closed, in the tripping chamber thus the same pressure resides as in the inlet port. This means that a force of pressure is exerted on the closing piston in the direction of the valve seat keeping the valve securely closed. The valve further comprises a tripping device which generates a pressure drop in the tripping chamber when a release is effected. After the reduction of the counter-pressure in the tripping chamber, a force of pressure acts on the closing piston which presses it away from its valve seat against a limit stop. By this action, the valve opens, so that the pressure medium can flow through the valve seat into the outlet port. The limit stop for the closing piston is formed by a sealing plate against which the mouth of the pressure compensation channel is pressed. That means that in this position the pressure compensation channel is sealed against the tripping chamber, so that no more counter-pressure can form in the tripping chamber, not even if the pressure is no longer reduced via the tripping device. In other words, the valve remains securely opened after the release. In order to close the valve of the emptied container, the tripping chamber is vented via the tripping device, so that a closing spring can press the closing piston onto the valve seat.
In stationary fire extinguishing plants, however, such differential pressure valves could not yet succeed as an alternative to articulated-lever valves. This is among others due to the fact that the filling of the pressure container with such differential pressure valves is relatively difficult. Indeed, the filling cannot be effected via the connecting piece of the valve, as in the process the closing piston would be pressed into its sealed end position and one would have no more possibility of closing the valve. It has therefore been proposed to arrange a separate filler port below the valve seat. However, even with this separate filler port, the filling must be effected extremely carefully, as in case of a fast increase of pressure in the filler port, the closing piston can be lifted from its valve seat.
Therefore, the object, among others, underlying the present invention is to propose a container valve with a tripping device for stationary fire extinguishing plants in a differential pressure construction which enables an easy filling of the container.
According to the invention, this object is achieved by a valve according to claim 1. The valve according to the invention also comprises, as do the differential pressure valves described in the beginning, a sealing element which seals the pressure compensation channel in the closing piston, when the latter is in its end position. In contrast to the known valves, however, this sealing element is not fixed in the valve body but can be actuated from the outside between a sealing position and a filling position, wherein in the sealing position it seals the pressure compensation channel of the closing piston in the end position and in the filling position it trips the pressure compensation channel of the closing piston in the end position. Now, the valve can be directly filled via the outlet port. In correspondence to a preferred procedure, the sealing element is brought into its filling position before the filling operation. The dynamic forces exerted on the closing piston by the incoming filling flow are in fact in most cases sufficient for holding the closing piston in an open position against the action of the closing spring. If, however, the filling flow is interrupted, the dynamic forces of pressure acting on the closing piston disappear. The resultant of the static forces of pressure acting on the closing piston also equals zero as the sealing element is in the filling position and the container pressure can consequently constitute via the open pressure compensation channel in the tripping chamber. The closing piston is thus in pressure equilibrium and is now pressed onto the valve seat by the spring force of the closing spring. To summarize, one can say that the valve closes immediately after the interruption of the filling flow if the sealing element has been brought into its filling position before the filling operation. Instead of bringing the sealing element into its filling position before the filling, it is also possible to effect the filling with the sealing element being in the sealing position. For the valve to close, the sealing element then has to be brought into the filling position after the interruption of the filling flow. This procedure is to be employed if the forces of flow during the filling are not sufficient for retaining the closing piston in an open position. With both procedures, the sealing element is returned to its sealing position after the filling in order to prepare the valve for the next release.
The sealing element can still be a sealing plate against which the mouth of the pressure compensation channel is pressed. In this embodiment, however, there is the problem that this sealing plate also has to fulfill the function of a buffer for the accelerated closing piston. In the process, the sealing plate is in most cases deformed by the relatively small sealing face surrounding the mouth of the pressure compensation channel such that it has to be exchanged already after the first release of the valve. The present invention has also solved this problem. That is, it is proposed to form the sealing element by a pin in the tripping chamber which can be introduced into the pressure compensation channel, the sealing being effected radially via an O-ring. In this embodiment with a radial sealing, the sealing element no longer has to fulfill a buffer function so that it does not have to be exchanged after every release. A separate annular buffer element which has essentially the same external diameter as the tripping chamber and thus a relatively large buffer face can then far more effectively cushion the impact of the closing piston on the limit stop.
The tripping device advantageously comprises a control valve integrated in the container valve and advantageously having the following design. A vent channel ends in the tripping chamber, a control valve seat facing the tripping chamber. A closing body is assigned to the control valve seat such that the pressure in the tripping chamber presses the closing body axially against the control valve seat of the vent channel, wherein the closing body seals the vent channel. An operating tappet to be accessed from the outside makes it possible to press the closing body away from its control valve seat in order to vent the tripping chamber.
A particular compact and simple valve design is achieved by arranging the control valve in the axial extension of the pressure compensation channel and forming the sealing element by a pin at the closing body of the control valve. As already described above, this pin can be axially introduced into the pressure compensation channel of the closing piston, the sealing between the pin and the pressure compensation channel being effected radially via an O-ring.
In an advantageous, particularly simple embodiment, this control valve then furthermore comprises a control valve body in which the vent channel and the control valve seat are arranged, with this control valve body being screwed from the outside between a first and a second position. In the first position, the pin seals the pressure compensation channel via the O-ring if the closing body abuts the control valve seat and the closing piston is in its end position. In the second position, the pin opens the pressure compensation channel to the tripping chamber if the closing body abuts the control valve seat and the closing piston is in its end position.
The tripping device further comprises an operating device for the control valve, which can be simply pinned onto the valve body in an advantageous embodiment. The control valve body is in this case advantageously embodied such that in the second position it projects further from the valve body than in the first position. This avoids a pinning of the operating device onto the valve body as long as the valve body is not screwed back into its first position in order to prepare the valve for the next release.